JP2000046584A - Position detection device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to perform a highly accurate position detection in a position detection device including a resolver. In order to improve the accuracy of position detection, output waveforms from an A-phase coil 13 and a B-phase coil 14 are phase-adjusted by phase adjustment circuits 27 and 28, respectively, to remove phase distortion and gain. The adjustment circuits 29 and 30 remove variations in amplitude.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position detecting device, and more particularly to a method of extracting a sine wave out of phase by 90.degree. By two coils arranged at positions shifted from each other, and performing position detection using the sine wave. The present invention relates to a position detecting device as described above.

[0002]

2. Description of the Related Art There is known a position detecting device called a resolver in which two coils are used to extract a sine wave whose phase is shifted by 90 °. As shown in FIG. 9, the position detecting device includes an A-phase coil 1 and a B-phase coil 2, and applies an AC signal having a reference frequency to each of the coils 1 and 2 to move the coils 1 and 2. , 2
Is amplitude-modulated. Outputs of the coils 1 and 2 are demodulated by differentiators 3 and 4, respectively, and supplied to a decoder 7 through low-pass filters 5 and 6, so that the decoder 7 obtains position data.

[0003]

According to the conventional resolver as shown in FIG. 9, distortion is generated in a sine wave to be taken out due to the gap between the stator and the mover and the shape of the tooth shape of the stator. I was If the angle detection or the position detection is performed using a sine wave having such a distortion, an error occurs and there is a problem that the accuracy is limited.

In view of such problems, conventionally, as shown in FIG. 9, low-pass filters 5 and 6 are provided, and the sine waves demodulated by the differentiators 3 and 4 by these filters 5 and 6 are filtered. Then, the required accuracy is obtained by reducing the distortion. However, according to such a method, there is a problem that it is difficult to correct different distortion waveforms specific to each resolver. For this reason, when manufacturing the resolver, the finishing of the teeth of the stator and the mover, the adjustment of the gap, and the like have to be performed with high accuracy, which requires man-hours and increases the cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is intended to electrically reduce the distortion of a sine wave taken out of two coils arranged at positions shifted from each other. It is an object of the present invention to provide a position detecting device that improves the accuracy.

[0006]

According to the present invention, a sine wave whose phase is shifted by 90 ° is extracted by two coils arranged at positions shifted from each other, and a position is detected using the sine wave. The present invention relates to a position detecting device provided with means for adjusting the phases of the two sine waves whose phases are shifted by 90 °. Here, the means for adjusting the phase may be a phase adjustment circuit.

Another aspect of the present invention is a position detecting device which extracts a sine wave whose phase is shifted by 90 ° by two coils arranged at positions shifted from each other, and performs position detection using the sine wave. The present invention relates to a position detecting device provided with means for adjusting the amplitudes of the two sine waves whose phases are shifted by 90 °. Here, the means for adjusting the amplitude may be a gain adjustment circuit.

Still another aspect of the present invention is a position detecting apparatus which extracts a sine wave whose phase is shifted by 90 ° by two coils arranged at positions shifted from each other, and performs position detection using the sine wave. The present invention relates to a position detection device characterized in that position data is corrected using correction data created in advance.

In another aspect, an A-phase coil and a B-phase coil are provided on one of the fixed side and the movable side so that the phases are shifted from each other by 90 °, and an AC signal of a predetermined frequency is supplied to the A-phase coil. And the amplitude of the AC signal applied to the A-phase coil and the B-phase coil when the mover is moved relative to the stator. By demodulating the output waveform of the A-phase coil and the output waveform of the B-phase coil, two sine waves having phases shifted by 90 ° are taken out, and position detection is performed from the level of the sine wave. And a means for adjusting the phase of the two sine waves whose phases are shifted by 90 ° and a means for adjusting the amplitude.

In a preferred aspect of the present invention, in a position detecting device comprising a resolver, a circuit for adjusting a two-phase wave output from the resolver, an electric circuit for converting the two-phase wave to a position, and a control means for controlling these circuits And a position detecting device comprising: Here, a position detecting device comprising a resolver has a circuit for adjusting the phase distortion and the amplitude distortion of the two sine waves, and further outputs the output obtained from the decoder that extracts the position information using the two sine waves. The correction is made by wear control.

According to such a configuration, it is possible to improve the influence of variations in the tooth shape of the stator and the mover and the coil, which can be dealt with only by improving the physical characteristics until now. Further, the accuracy can be further improved by using the correction by software control together.

In a position detecting device including a resolver used for position detection of an XY table, a radar antenna, a slide mechanism, and the like, when detecting a position or an angle using a sine wave whose phase is shifted by 90 °, a sine wave is detected. Accuracy deteriorates if there is amplitude or phase distortion. For this purpose, accuracy is obtained by devising a mechanism of a detecting unit for reducing the distortion of the sine wave, or reducing the distortion by filtering the waveform. For this reason, it is necessary to increase the precision of the gap and the shape of the detection unit, which causes a problem of increasing the manufacturing cost. In the case of the linear type, teeth are cut to the stator and mover of the resolver in order to generate a sine wave to the detection coil. Because of the change, the reproducibility of the sine wave is poor, and the position fluctuates, which causes the accuracy to deteriorate.

In the present invention, in order to solve the above problems, attention is paid to the phase distortion and the amplitude distortion of the sine wave output from the two coils, and these phase distortions and amplitude distortions are reduced. The present invention provides a position detecting device in which the phase and amplitude of a phase wave are individually varied, thereby having a function of reducing distortion of a two-phase wave.

The two-phase coil has, for example, 10K.
Hz AC signal is supplied from an AC signal source. The reactance changes due to the action of the teeth of the stator 10 and the mover 17, and the amplitude of the alternating current changes. Since the two-phase wave coil is arranged with a phase shifted by 90 °, a two-phase wave with a phase shifted by 90 ° can be obtained by extracting the two-phase coil with a differentiator. The phase of the two-phase wave does not always coincide with 90 ° due to an error in the tooth shape and the variation of the coil, and the amplitude also varies.

Therefore, the phase difference between the two sine waves is correctly adjusted to 90 ° by the phase adjustment circuit, and the amplitude of the two sine waves is adjusted by the gain adjustment circuit so as to be the same. The thus obtained two-phase wave with small distortion is converted into a position or an angle by a decoder. By correcting the error of the position or angle data thus obtained by software, it is possible to detect the position with high accuracy.

[0016]

FIG. 1 shows in principle a position detecting apparatus according to an embodiment of the present invention. This detection device is a position detection device called a so-called resolver, and includes a stator 10. A pair of salient poles 11 and 12 are connected to the stator 10, and an A-phase coil 13 and a B-phase coil 14 are wound around these salient poles 11 and 12, respectively. Further, teeth 15 and 16 are formed at a predetermined pitch in a portion on the tip side of the salient pole 11.

On the other hand, a mover 17 is arranged to face the stator 10. The movable element 17 has teeth 1 facing the teeth 15 and 16 of the salient poles 11 and 12.
8 are formed. Here, the pitch of the teeth 18 is the same as the pitch of the teeth 15 and 16 of the salient poles 11 and 12.
Moreover, when the teeth 18 of the mover 17 coincide with the teeth 15 of the salient pole 11, the teeth 16 of the salient pole 12
The pitch is shifted by 8 and 1/4 pitch. That is, if the pitch of the teeth is 2π, the positions of the teeth 16 are shifted by π / 2.

The two salient poles 11 of such a stator 10
Sinusoidal waves whose phases are shifted from each other by 90 ° are extracted from the coils 13 and 14 wound around the respective coils 12. That is, as shown in FIG. 2, the output of the A phase and the output of the B phase are extracted in a state of being shifted by π / 2. Therefore tooth 1
Assuming that the pitches of 5, 16, and 18 correspond to π / 2, the output of the B phase is Y, and the output of the A phase is X, the position of the mover 17 is (X,
Y).

Here, Y = sin θ X = cos θ tan θ = Y / X θ = tan ⁻¹ Y / X Therefore, the output of the A phase and the output of the B phase when the movable element 17 has moved to an arbitrary position can be detected. Thus, the position of the mover 17 can be obtained from the above equation.

FIG. 4 shows a specific circuit configuration for such position detection. An AC signal source 22 is connected to the A-phase coil 13 and the B-phase coil 14, respectively. The output terminals of the A-phase coil 13 and the B-phase coil 14 are connected to differentiators 23 and 24, respectively.
These differentiators 23 and 24 are low-pass filters 25 and 2
6 is connected. Furthermore, low-pass filters 25, 2
6 is connected to position adjustment circuits 27 and 28. The position adjustment circuits 27 and 28 are further connected to gain adjustment circuits 29 and 30. The outputs of the gain adjustment circuits 29 and 30 are input to the decoder 31. The decoder 31 outputs two sine waves,
The position of the mover 17 is obtained by calculation.

Next, the operation of the circuit shown in FIG. 4 will be described. A predetermined frequency, for example, 10 KHz by the AC signal source 22
The AC reference signal of the A phase coil 13 and the B phase coil 1
And 4 respectively. At this time, it is assumed that the teeth 15 of the A-phase coil 13 completely coincide with the teeth 18 of the mover 17, as shown in FIG. Then, since the magnetic resistance between the salient pole 11 and the mover 17 is minimized, the output of the A-phase coil 13 has a large amplitude waveform as shown in FIG. 5A. On the other hand, the teeth 16 of the salient pole 12
Is shifted from the teeth 18 of the mover 17 by π / 2,
The output of the phase coil 14 has a very small value as shown in FIG. 5B.

Therefore, when the movable element 17 is moved relative to the stator 10 in the left or right direction as shown by the arrow in FIG. 1, the movable element 17 is added to the A-phase coil 13 and the B-phase coil 14, respectively. The AC signal is amplitude-modulated as shown in FIG. 5C. That is, as the teeth 15, 16 of the salient poles 11, 12 coincide with or deviate from the teeth 18 of the mover 17, the output changes because the magnetic resistance changes. As a result, the AC signal applied from the outside is amplitude-modulated as shown in FIG. 5C.

The output of the A-phase coil 13 is
3, demodulation by 3 gives an A-phase sine wave, and demodulation of the output of the B-phase coil 14 by a differentiator 24 gives a B-phase sine wave. These sine waves are the two sine waves shown in FIG.

These sine waves are removed of noise by low-pass filters 25 and 26, respectively, phase-adjusted by phase adjustment circuits 27 and 28, and gains are adjusted by gain adjustment circuits 29 and 30. Then, the two sine waves subjected to the phase adjustment and the gain adjustment are supplied to the decoder 31, thereby obtaining position detection information.

The reason for providing the phase adjusting circuits 27 and 28 is as follows. That is, the teeth 15, 16 of the salient poles 11, 12
Is completely shifted by π / 2, there is no need to perform phase adjustment. However, actually, teeth 15, 16
Is very fine, and even if such fine teeth are shifted from each other by π / 2, they are not always exactly π / 2 shifted. Therefore, such variations in the precision of the teeth 15 and 16 occur. Such a variation is caused by the phase adjustment circuit 2
The correction is made at 7, 28.

Next, the gain adjustment circuits 29 and 30 are provided for the following reason. That is, both the A-phase coil 13 and the B-phase coil 14 are 3.5 at 10 KHz, for example.
Even if a voltage having an amplitude of V is applied, the output is not always constant. That is, the winding method of the coil and the salient poles 11,
The amplitude of the output of the A-phase coil 13 and the amplitude of the output of the B-phase coil 14 vary due to the variation of the 12 cores or the variation of the circuit. Such variations result in errors in the position data. Therefore, gain adjustment circuits 29 and 30 are provided to absorb such errors.

As described above, the position detecting device of the present embodiment is constituted by the resolver including the movable element 17 and the stator 10 which move linearly as shown in FIG. 1, and detects the position of the movable element 17. It is for. Here, to detect the position, a two-phase wave generated by the resolver coils 13 and 14 with a phase shift of π / 2 is input to a dedicated decoder 31.
Here, decoding is performed to obtain position detection data. The resolver coils 13 and 14 are salient poles 11 made of silicon steel,
The winding 12 is provided with teeth 15 and 16 so as to obtain a sinusoidal output as shown in FIG. Since the phases are two, the teeth 15 and 16 are arranged so as to be out of phase by 90 °.

The electrical characteristics of the two coils 13 and 14 vary somewhat. When these two coils are excited at a fixed frequency and the mover 17 is moved, the output wave is amplitude-modulated as shown in FIG. 5C. By demodulating this with the differentiators 23 and 24, a two-phase wave as shown in FIG. 2 is obtained.

The two-phase waves obtained here are the coils 13 and 14
Due to differences in the characteristics of the above and the errors of the teeth 15 and 16, there are variations in phase and amplitude. Therefore, the phase adjustment circuit 2
The position information is obtained by reducing the phase shift and the variation in the amplitude between the gain adjustment circuits 7 and 28 and the gain adjustment circuits 29 and 30 and then inputting the information to the decoder 31, thereby obtaining a highly accurate position information output. Will be.

Further, in this embodiment, the position information is further processed by software to reduce the error. Since a portion having repeatability due to a resolver error can be corrected, it is possible to improve the software by providing a correction function. First, a reference length measuring device for correcting the position data of the resolver is installed. Next, position data is measured and compared over the entire length of the resolver to generate correction data. This is averaged for each tooth to generate correction data. This is added as a correction value each time the position data is read, so that the position is corrected.

FIG. 6 shows a control program for reducing such an error. First, a position correction table is created, and the current position is read from the decoder 31. Then, position correction is performed by a position correction routine, and then control calculation is performed. This calculation is a calculation of the output current. At this time, it is determined whether the servo is operating or not, and if the servo is operating, it is output to the amplifier. On the other hand, when the servo is not operated, the process returns to the step of reading the current position.

FIG. 7 shows a position correction routine, in which a correction value corresponding to the current position is read and a correction value corresponding to the current position is obtained by interpolating the correction value as shown in FIG. . Then, a correction value is added to the current position, thereby reducing the error.

Although the present invention has been described with reference to one embodiment shown in the drawings, the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above-described embodiment, the position is detected when the mover 17 is linearly moved. However, the position detecting device is a rotary position detecting device that performs angle detection. The present invention is also applicable to the present invention.

[0034]

As described above, according to the present invention, a sine wave whose phase is shifted by 90 ° is extracted by two coils arranged at positions shifted from each other, and the position is detected using the sine wave. In the detection device, means for adjusting the phase of two sine waves having phases shifted by 90 ° is provided.

Therefore, it is possible to correct the difference between the two sine waves due to the mechanical phase shift, and to correctly adjust the phase difference to a value of 90 °.

According to the configuration in which the means for adjusting the phase is a phase adjusting circuit, such a phase adjusting circuit can make 90 °
Is held at the phase difference of

Another aspect of the present invention is a position detecting apparatus which extracts a sine wave having a phase shift of 90 ° by two coils arranged at positions shifted from each other and performs position detection using the sine wave. A means for adjusting the amplitudes of two sine waves out of phase is provided.

Therefore, according to such a configuration, it is possible to absorb the variation in the amplitude of the output of the two coils.

According to the configuration in which the means for adjusting the amplitude is a gain adjustment circuit, such a gain adjustment circuit can
Adjustment of the amplitude of the two sine waves is performed.

Still another aspect of the present invention is a position detecting device which extracts a sine wave having a phase shift of 90 ° by two coils arranged at positions shifted from each other, and performs position detection using the sine wave. The position data is corrected using correction data created in advance.

Therefore, by correcting the position data based on such correction data, more accurate position detection can be performed.

According to still another invention, an A-phase coil and a B-phase coil are provided on one of the fixed side and the movable side so that the phases are shifted from each other by 90 °, and an AC signal of a predetermined frequency is supplied to the A-phase coil. The AC signals applied to the A-phase coil and the B-phase coil are amplitude-modulated when the mover is moved with respect to the stator, and the amplitude-modulated A-phase By demodulating the output waveform of the coil and the output waveform of the B-phase coil respectively, 2
In a position detecting device that takes out two sine waves and performs position detection from the level of the sine waves, a means for adjusting the phase of two sine waves having a 90 ° phase shift and a means for adjusting the amplitude are provided. Things.

Therefore, according to the present invention, the phase shift between two sine waves can be set correctly, and the variation in the amplitude of these sine waves can be absorbed, whereby more accurate position detection can be performed. .

[Brief description of the drawings]

FIG. 1 is a plan view of a position detection device.

FIG. 2 is a graph showing output waveforms of two coils.

FIG. 3 is a graph showing a relationship between waveforms of two coils and angles of polar coordinates.

FIG. 4 is a block diagram showing a circuit for position detection.

FIG. 5 is a waveform chart showing an operation of the circuit.

FIG. 6 is a flowchart illustrating a control operation of position correction.

FIG. 7 is a flowchart illustrating a position correction routine.

FIG. 8 is a graph showing an operation of position correction.

FIG. 9 is a block diagram of a conventional position detection circuit.

[Explanation of symbols]

1 ‥‥ coil (A phase), 2 ‥‥ coil (B phase), 3, 4
{Differentiator, 5, 6} Low-pass filter, 7} Decoder, 10} Stator, 11, 12} Salient pole, 13}
Coil (A phase), 14 ° coil (B phase), 15, 16
{Tooth, 17} mover, 18} tooth, 22} AC signal source, 23, 24 differencer, 25, 26 low pass filter, 27, 28 phase adjustment circuit, 29, 30 ‥
{Gain adjustment circuit, 31} decoder

Claims (6)

[Claims] 1. A position detecting device which extracts a sine wave having a phase shift of 90 ° by two coils disposed at positions shifted from each other, and performs position detection using the sine wave. A position detecting device provided with means for adjusting the phases of two sine waves having different positions. 2. The position detecting device according to claim 1, wherein said means for adjusting the phase is a phase adjusting circuit. 3. A position detecting apparatus for extracting a sine wave having a phase shifted by 90 ° by two coils arranged at positions shifted from each other and performing position detection using the sine wave. A position detecting device provided with a means for adjusting the amplitudes of the two sine waves having different positions. 4. The position detecting device according to claim 3, wherein said means for adjusting the amplitude is a gain adjusting circuit. 5. A position detecting device which extracts a sine wave whose phase is shifted by 90 ° by two coils arranged at positions shifted from each other, and performs position detection using the sine wave. A position detecting device wherein position data is corrected using correction data. 6. An A-phase coil and a B-phase coil are provided on one of the fixed side and the movable side such that the phases are shifted from each other by 90 °, and an AC signal of a predetermined frequency is supplied to the A-phase coil and the A-phase coil. The AC signal applied to the A-phase coil and the B-phase coil is amplitude-modulated when the mover is moved relative to the stator while being applied to the B-phase coil. By demodulating the output waveform of the phase coil and the output waveform of the phase B coil, respectively,
In a position detecting apparatus which extracts two sine waves having a phase shift of 0 ° and performs position detection from the level of the sine wave, means for adjusting the phase of the two sine waves having a phase shift of 90 ° and amplitude And a means for adjusting the position.